LISBON: Pope John Paul I, who died from an apparent heart attack just 33 days after becoming pontiff in 1978, was assassinated because of his plans to radically reform the Catholic church, according to a novel to be published next year.

Portuguese author and scriptwriter Luis Miguel Rocha said he based The Last Pope on documents he obtained through an undisclosed Vatican source, which he will make public when the novel is published in April.

The novel puts the theory that John Paul I had become a threat because he was aware of moneylaundering involving the Vatican Bank and also because of his plans to liberalise aspects of centuries-old church doctrine.

"He wanted to be the last wealthy pope. John Paul I wanted to redistribute the riches of the church, open the church to women and authorise the use of contraceptives," said Rocha, 29, in a weekend interview.

The novel depicts John Paul I's assassination as the result of a conspiracy involving top financial officials, several European governments and a Mafia group that counted top officials of the Roman Curia, including the pontiff's personal secretary, among its members.

John Paul I's death on September 28, 1978, caused widespread speculation due to discrepancies between the official account of the discovery of his body and the facts, combined with the Vatican's refusal to perform an autopsy.

Rocha's book is not the first to point to foul play.

In 1984, British author David Yallop, who writes mostly about unsolved crimes, published In God's Name, which proposed the theory that John Paul I's death was linked to corruption at the Vatican Bank.

Many of its points of suspicion, however, were challenged four years later by British historian and journalist John Cornwell in his book A Thief in the Night.